Deliniation

Wetland definition USACE

areas saturated long enough to support vegetation adapted to saturated soils

Wetland definition key factors

soils vegetation hydrology must indicate saturation

Wetland delineation purpose

identify upper boundary of a wetland for regulation inventory assessment management

Wetland soil definition

soils saturated long enough during growing season to develop anaerobic conditions

Histosols

soils with more than half of upper 32 inches composed of organic matter

Histic epipedon

8 to 16 inch surface layer saturated 30 days per year with high organic matter

Eluviation

removal of materials from upper soil horizons by water

Illuviation

deposition of materials into lower soil horizons

Mottled soils

soils with mixed colors indicating fluctuating water table

Gleyed soils

gray bluish or greenish soils formed under anaerobic conditions

Gley significance

indicates long term saturation and wetland soil conditions

Sulfidic material

rotten egg odor from hydrogen sulfide in permanently saturated reducing soils

Aquic moisture regime

soil saturated and oxygen free due to groundwater

Peraquic moisture regime

groundwater always at or near soil surface

Iron manganese concretions

black or brown masses formed during redox processes indicating saturation

Sandy soil exception

sandy soils need additional indicators due to low water holding capacity

Sandy soil indicators

high organic matter organic pans streaking by organic matter

Wetland hydrology requirement

one primary or two secondary indicators needed

Primary indicator inundation

visible standing water

Primary indicator saturation

visible soil saturation in top 12 inches

Primary indicator watermarks

stains on vegetation showing past water levels

Primary indicator drift lines

debris deposited in lines after flooding

Primary indicator sediment deposits

thin layers of mineral or organic matter left after inundation

Primary indicator drainage patterns

flow paths visible within wetland

Secondary indicator oxidized rhizosphere

orange zones around living roots in upper soil

Secondary indicator water stained leaves

leaves showing prolonged water exposure

Secondary indicator soil survey data

hydrology information from mapped soils

Secondary indicator plant adaptations

presence of hydrophytic traits

Hydrophytic vegetation definition

plants adapted to anaerobic saturated soils

Hydrophytic adaptations

buttressed trunks shallow roots floating leaves

Aerenchyma

spongy tissue transporting air from stems to roots

Obligate wetland plants

species found in wetlands 100 percent of the time

Facultative wetland plants

species found in wetlands 66 to 99 percent of the time

Mixed vegetation indicator

mixture of facultative and upland species requires closer evaluation